Iran's Foreign Minister Mohammad Javad Zarif called Monday on the bloc's top envoy Josep Borrell to coordinate a synchronised return of Washington into the 2015 agreement and Tehran's full compliance with it.

The EU, which coordinates implementation of the deal, has been scrambling along with world powers who signed it to save the pact since former US leader Donald Trump pulled out in 2018 and slapped tough sanctions on Iran.

EU foreign policy chief Josep Borrell was "working extremely hard to get the JCPOA back on the rails," a spokesman for Borrell said, using the official name for the accord.

"We're talking to the American administration to see if those sanctions could be lifted, to see if we can have full implementation of the JCPOA," said the spokesman, Peter Stano.

Biden has voiced support for returning to the accord, but has insisted that Tehran first come back into compliance by reversing measures it took to protest the sweeping US sanctions.